Usage: perl ascendoly.pl file

ascendoly.pl

use strict;
use warnings;

open my $fh, "<", $ARGV[0] or die $!;
my $data;
while(<$fh>) {
    s/[\r\n]//g;
    my (undef, $id1, $id2) = split '\s+', $_;
    push @{ $data->{$id2} }, $id1;
}

for my $key (sort keys %{ $data }) {
    print join("\t", $key, @{ $data->{$key} })."\n";
}